Scanning probe microscopes scan a specimen or its surface with a probe and thus produce a representation of properties of the specimen. Below, scanning probe microscopes are abbreviated SPM. Different SPM types are differentiated depending on the type of interaction between the measuring tip of a probe and the specimen surface. Use is often made of scanning tunneling microscopes (STMs), atomic force microscopes (AFMs) or scanning force microscopes (SFMs). In addition to these conventional SPM types, there are a multiplicity of further appliance types which are used for specific fields of application, such as e.g. magnetic force microscopes or optical and acoustic near-field scanning microscopes. Special scanning probe microscope probes which have also been designed for modifying a specimen in addition to analyzing the specimen surface have been developed.
Probes for the aforementioned scanning probe microscopes are often exposed to wear-and-tear, can become dirty or be damaged during operation. Thus, for example, tips for scanning tunneling microscopy or scanning force microscopy can become blunt or unusable in any other way. Therefore, it is useful to be able to replace probes quickly and without much outlay.
A probe interchange is difficult for, in particular, scanning probe microscopes that are used in vacuum surroundings if the system has to be aerated to this end. Therefore, the prior art has disclosed the use of probe arrays which have a multiplicity of probes. Examples thereof are described in the documents WO 02/080187 A1, WO 2008/053217 A1, US 2013/0014296 A1, and US 2013/0111635 A1. However, the production of probe arrays or probe arrangements is complicated. Moreover, their usage options can be restricted due to the spatial requirements of the probe arrays and/or their large mass.
In the article “Electromagnetic changer for AFM tips”, the authors B. Goj, N. Vorbringer-Dorozhovets, C. Wystup, M. Hoffmann and E. Manske, in Proceedings of Micromechanics and Microsystems Europe Workshop 2012, ISBN: 978-3-938843-71-0 (https://www.tu-ilmenau.de/en/micromechanical-systems-group/publications/conferences), report about the design of an electromagnetic holding apparatus, with the aid of which a probe can be releasably fastened to the head of a scanning force microscope.
US 2007/0022804 A1 describes an apparatus which facilitates an automated interchange of the probe. The probes are held in a storage space by a spring, air, gravity, electromechanically or by vacuum-driven deposition mechanisms.
U.S. Pat. No. 5,705,814 describes a scanning probe microscope for an automated probe interchange. To this end, the SPM has a storage cassette for probes, in which a plurality of probes can be deposited. The probes are held in the storage cassette by vacuum-based, mechanical, electrostatic, magnetic or electromagnetic clamping. The free end of a scanner has a probe holder. The latter can hold a probe by use of negative pressure or mechanical, magnetic, electrostatic or electromagnetic clamping or by use of weak adhesives.
In the case of a magnetic holder of a probe, the contact between the probe and a permanent magnet is effectuated, as a rule, by use of a jerky movement of the probe which, depending on the strength of the magnet, can overcome a distance up to several millimeters. As a result, particles are often released, said particles possibly reaching a specimen to be examined and possibly causing a significant contamination problem. Moreover, this movement is uncontrolled and therefore leads to an at least partly unknown alignment of the probe relative to the probe holder. In order to avoid this problem, U.S. Pat. No. 5,705,814 proposes the use of an adjustable electromagnetic holder instead of a magnetic holder for the purposes of anchoring the probe to the probe holder.
U.S. Pat. No. 8,099,793 B2 describes an automated probe interchange system on the basis of permanent magnets. In order to establish a differential magnetic force between the probe holder of a scanning probe microscope and a probe holder of a probe repository, said magnetic force transferring a probe from the probe holder of the SPM to the probe holder of the probe repository, or vice versa, the permanent magnets of the probe repository are moved in the vertical direction. This is a disadvantage of the method described in the aforementioned patent document since, in addition to the movement of the probe repository, the permanent magnets thereof must also be moved relative to the probe repository by use of a complicated movement mechanism. Moreover, a complicated and accurate teach-in of the transfer position of the probe from the probe repository to the SPM, or vice versa, is required. If the transfer position is determined incorrectly, there is the risk of damage to the interchange mechanism or sensitive components of the complex AFM head.
The information provided above is merely to assist the reader in understanding the background of the invention. Some of the information provided in this “Background” section may not be prior art to the invention.
Therefore, the present invention is based on the problem of specifying a probe system and a method for receiving a probe of a scanning probe microscope which at least partly avoid the aforementioned disadvantages.